In the related art, heating furnaces including gas heaters used to heat a radiator with combustion heat generated by combusting a fuel gas and heating an industrial material, food, or the like, with radiant heat from a radiation surface of the radiator have been widely distributed.
In addition, a heating furnace configured to circulate a hot wind heated by an electric heater as well as a gas heater into a duct in which a burning target is placed and transfer radiant heat from the heated duct to the burning target has been proposed (for example, Patent Document 1).